• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1270-1275
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• 2013

A lot of research about camera calibration and lens distortion for wide-angle lens has been made. Especially, calibration for fish-eye lens which has 180 degree FOV(field of view) or above is more tricky, so existing research employed a huge calibration pattern or even 3D pattern. And it is important that calibration parameters (such as distortion coefficients) are suitably initialized to get accurate calibration results. It can be achieved by using manufacturer information or lease-square method for relatively narrow FOV(135, 150 degree) lens. In this paper, without any previous manufacturer information, camera calibration and barrel undistortion for fish-eye lens with over 180 degree FOV are achieved by only using one calibration pattern image. We applied QR decomposition for initialization and Regularization for optimization. With the result of experiment, we verified that our algorithm can achieve camera calibration and image undistortion successfully.

• Journal of the Korean Applied Science and Technology
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• v.26 no.2
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• pp.205-212
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• 2009

Solution copolymerization of Styrene(St.) with 2-Hydroxypropylacrylate(2-HPA) was carried out with Benzoylperoxide(BPO) as an initiator in toluene at $80^{\circ}C$ in a batch reactor. Reaction volume and reaction time were 0.3 liters, 8 hours respectively. The time to reach steady state was about the six time. The monomer reactivity ratios, $r_1$(St.) and $r_2$(2-HPA) were determined by both the Kelen-Tudos method and the Fineman-Ross method ; $r_1$(St.)=0.376(0.330), $r_2$(2-HPA)=0.408(0.778). The activation energy of thermal decomposition was in the range of $33{\sim}55kcal/mol$.

• Journal of the Korean Operations Research and Management Science Society
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• v.11 no.1
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• pp.24-35
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• 1986

We investigate various methods of the Benders decoposition algorithm in its application to the simple plant location problem. We developed six variants. The master problem may be relaxed as an LP problem up to an appropriate point in time, or need not be solved to the optimality before a cut is added. Furthermore, since the subproblem is highly degenerated, we can generate more than one cuts at a time. The efficiency of the methods are examined using a sample problem. The result showed that the adding two-cut method was superior to the standard method. The LP relaxation and the non-optimization of the master program greatly improved the efficiency. Applying the LP relaxation method, we were able to reduce the computing time by two thirds of the time required by the standard method.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.3
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• pp.146-152
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• 2011

Thermal stability of $Ge_2Sb_2Te_5$ (GST) and $SiO_2$ doped GST (SGST) films for phase change random access memory applications was investigated by observing the change of surface roughness, layer density and composition of both films after isothermal annealing. After both GST and SGST films were annealed at $325^{\circ}C$ for 20 min, root mean square (RMS) surface roughness of GST was increased from 1.9 to 35.9 nm but that of SGST was almost unchanged. Layer density of GST also steeply decreased from 72.48 to 68.98 $g/cm^2$ and composition was largely varied from Ge : Sb : Te = 22.3 : 22.1 : 55.6 to 24.2 : 22.7 : 53.1, while those of SGST were almost unchanged. It was confirmed that the addition of a small amount of $SiO_2$ into GST film restricted the deterioration of physical and chemical properties of GST film, resulting in the better thermal stability after isothermal annealing.

• Journal of the Korean School Mathematics Society
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• v.8 no.3
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• pp.315-325
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• 2005

In school education, mathematics is obviously an independent subject. But the function of mathematics is revealed when it is joined with other subject. For example, when we use mathematics to solve a scientific problem, we can clearly feel the function of mathematics and its roll for science. So, it is general to teach the functions of mathematics by dealing mathematical application. For this method, student mostly pass over that because mathematics is only a tool. Therefore, it is necessary for mathematics part to be separated from mixed application. In this paper, we present a model to contain such an effect.